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At a glance

This is a medical condition characterized by ventricular preexcitation conduction defects, associated with a short P-R interval and a wide QRS complex. It is reported that 40% of individuals affected with this electrical problem never develop symptoms. The clinical features include palpitations at rest, dyspnea, headache, and syncope. Ultimately, cardiac arrest may occur with sudden death. The risk of death in those without symptoms is about 0.5% per year in children and 0.1% per year in adults. The most common type of arrhythmia is determined as paroxysmal supraventricular tachycardia. The cardiac anomaly most frequently associated with this problem is Ebstein’s anomaly.

Synonym

WPW Syndrome.

History

In 1915, Frank Norman Wilson (1890-1952) was the first to describe this arrhythmic condition that was later called Wolff-Parkinson-White Syndrome. Alfred M. Wedd (1887-1967) subsequently reported this condition in 1921. Surprisingly, this medical condition was credited to the cardiologists Louis Wolff (1898-1972), John Parkinson (1885-1976), and Paul Dudley White (1886-1973) in 1930 when they reported the first ECG recording. The bundle of Kent is eponymously named for British physiologist Albert Frank Stanley Kent (1863-1958), who described the presence of lateral branches in the atrioventricular groove of the monkey heart (erroneously believing these constituted the normal atrioventricular conduction system).

Incidence

Incidence 1 to 3:1,000 in a general population. The risk of death in those without symptoms is about 0.5% per year in children and 0.1% per year in adults.

Genetic inheritance

Unclear, an autosomal dominant inheritance is suggested by some kindreds. It is believed to be caused by a mutation in the gamma-2 regulatory subunit of AMP-activated protein kinase (PRKAG) located on 7q36.

Pathophysiology

During fetal life, numerous connections link the atria to the ventricles, but they all disappear before birth except for the bundle of His. Sometimes, some of the connections do not disappear. This accessory pathway(s) characterizes the Wolff-Parkinson-White Syndrome. An accessory atrioventricular connection (bundle of Kent) bypasses the atrioventricular node, and inserts directly into myocardium (consistent with bypass tracts in Lown-Ganong-Levine Syndrome). The accessory bundle may conduct ante- or retrograde. Antegrade conduction causes early commencement of ventricular depolarization, seen as a delta wave on the ECG. Retrograde conduction allows a reentry circuit to develop and is a mechanism for paroxysmal tachycardia generation. The accessory connection may only conduct in a retrograde direction; therefore a delta wave will not appear on ECG. Such a tract is described as concealed. In atrial fibrillation, antegrade conduction along the accessory pathway may result in rapid ventricular rate, which is poorly tolerated.

Diagnosis

History, ECG findings of a short P-R interval, and a delta wave. Electrophysiology studies to define individual pathway anatomy and mechanism for dysrhythmia generation.

Clinical aspects

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